LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Dmitry Osipenko <digetx@gmail.com>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Linux PM <linux-pm@vger.kernel.org>,
	Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Rajendra Nayak <rnayak@codeaurora.org>,
	Stephan Gerhold <stephan@gerhold.net>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/3] PM: domains: Add a ->dev_get_performance_state() callback to genpd
Date: Fri, 3 Sep 2021 13:06:27 +0300	[thread overview]
Message-ID: <1124dae5-478f-f0ca-ea91-b6945f7c9254@gmail.com> (raw)
In-Reply-To: <CAPDyKFr2oQnKOhKhWt_9VyBoe=HQ7Y0uZUMKTcZ05a7G9RaBYA@mail.gmail.com>

03.09.2021 11:55, Ulf Hansson пишет:
> On Fri, 3 Sept 2021 at 08:00, Dmitry Osipenko <digetx@gmail.com> wrote:
>>
>> 02.09.2021 13:16, Ulf Hansson пишет:
>>> Hardware may be preprogrammed to a specific performance state, which may
>>> not be zero initially during boot. This may lead to that genpd's current
>>> performance state becomes inconsistent with the state of the hardware. To
>>> deal with this, the driver for a device that is being attached to its
>>> genpd, need to request an initial performance state vote, which is
>>> typically done by calling some of the OPP APIs while probing.
>>>
>>> In some cases this would lead to boilerplate code in the drivers. Let's
>>> make it possible to avoid this, by adding a new optional callback to genpd
>>> and invoke it per device during the attach process. In this way, the genpd
>>> provider driver can inform genpd about the initial performance state that
>>> is needed for the device.
>>>
>>> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
>>> ---
>>>  drivers/base/power/domain.c | 8 +++++---
>>>  include/linux/pm_domain.h   | 2 ++
>>>  2 files changed, 7 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
>>> index 800adf831cae..1a6f3538af8d 100644
>>> --- a/drivers/base/power/domain.c
>>> +++ b/drivers/base/power/domain.c
>>> @@ -2640,13 +2640,15 @@ static void genpd_dev_pm_sync(struct device *dev)
>>>       genpd_queue_power_off_work(pd);
>>>  }
>>>
>>> -static int genpd_get_default_performance_state(struct device *dev,
>>> +static int genpd_get_default_performance_state(struct generic_pm_domain *genpd,
>>> +                                            struct device *dev,
>>>                                              unsigned int index)
>>>  {
>>>       int pstate = of_get_required_opp_performance_state(dev->of_node, index);
>>>
>>>       if (pstate == -ENODEV || pstate == -EOPNOTSUPP)
>>> -             return 0;
>>> +             pstate = genpd->dev_get_performance_state ?
>>> +                      genpd->dev_get_performance_state(genpd, dev) : 0;
>>>
>>>       return pstate;
>>>  }
>>> @@ -2701,7 +2703,7 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
>>>       }
>>>
>>>       /* Set the default performance state */
>>> -     pstate = genpd_get_default_performance_state(dev, index);
>>> +     pstate = genpd_get_default_performance_state(pd, dev, index);
>>
>> If base device is suspended, then its performance state is zero.
>>
>> When device will be rpm-resumed, then its performance should be set to
>> the default state.
>> You're setting performance state of the wrong device, it should be the
Are you okay with my variant of handling the suspended device?


>> base device and not the virtual domain device.
> 
> No I am not. :-) Let me elaborate.
> 
> For the single PM domain case, 'dev' and 'base_dev' are pointing to
> the same device. So this works fine.
> 
> For the multiple PM domain case or when attaching goes via
> genpd_dev_pm_attach_by_id(), 'dev' is the virtual device registered in
> genpd_dev_pm_attach_by_id(). In this case, it's 'dev' that is becoming
> attached to genpd and not the 'base_dev'. Note also that, runtime PM
> has not been enabled for 'dev' yet at this point and 'dev' has been
> assigned the same OF node as 'base_dev", to allow OF parsing to work
> as is for it.
> 
> Moreover, to deal with runtime PM in the multiple PM domain case, the
> consumer driver should create a device link. Along the lines of this:
> device_link_add(base_dev, dev, DL_FLAG_PM_RUNTIME |
> DL_FLAG_STATELESS), thus assigning the virtual device ('dev') as the
> supplier for its consumer device ('base_dev').
> 
>>
>> These all is handled properly by my patch [1]. Hence it's complicated
>> for the reason.
> 
> See above. It shouldn't have to be complicated. If it still is, there
> is something to fix for the multiple PM domain case.
>> [1]
Alright, it actually works now on Tegra using the dev in the callback
for the case of multiple domains, I re-checked it. Previously, when I
tried that, there was a conflict in regards to OPP usage, I don't
remember details anymore. Maybe the recent changes that were suggested
by Viresh helped with that. So yes, there is no need to pass the base
device anymore.

  reply	other threads:[~2021-09-03 10:06 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-02 10:16 [PATCH 0/3] PM: domains: Improvements for performance states in genpd Ulf Hansson
2021-09-02 10:16 ` [PATCH 1/3] PM: domains: Drop the performance state vote for a device at detach Ulf Hansson
2021-09-03  6:01   ` Dmitry Osipenko
2021-09-03  8:22     ` Ulf Hansson
2021-09-03  9:58       ` Dmitry Osipenko
2021-09-03 14:03         ` Ulf Hansson
2021-09-05  8:26           ` Dmitry Osipenko
2021-09-06 10:24             ` Ulf Hansson
2021-09-06 14:11               ` Dmitry Osipenko
2021-09-06 17:34                 ` Ulf Hansson
2021-09-06 19:33                   ` Dmitry Osipenko
2021-09-07 10:16                     ` Ulf Hansson
2021-09-09 13:48                       ` Dmitry Osipenko
2021-09-09 14:45                         ` Ulf Hansson
2021-09-02 10:16 ` [PATCH 2/3] PM: domains: Restructure some code in __genpd_dev_pm_attach() Ulf Hansson
2021-09-02 10:16 ` [PATCH 3/3] PM: domains: Add a ->dev_get_performance_state() callback to genpd Ulf Hansson
2021-09-03  6:00   ` Dmitry Osipenko
2021-09-03  8:55     ` Ulf Hansson
2021-09-03 10:06       ` Dmitry Osipenko [this message]
2021-09-03 14:09         ` Ulf Hansson
2021-09-05  9:11           ` Dmitry Osipenko
2021-09-06 10:53             ` Ulf Hansson
2021-09-06 14:35               ` Dmitry Osipenko
2021-09-07  3:40                 ` Viresh Kumar
2021-09-07  8:10                   ` Dmitry Osipenko
2021-09-07  9:57                 ` Ulf Hansson
2021-09-09 13:48                   ` Dmitry Osipenko
2021-09-09 14:39                     ` Ulf Hansson
2021-09-10 11:24                       ` Dmitry Osipenko

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1124dae5-478f-f0ca-ea91-b6945f7c9254@gmail.com \
    --to=digetx@gmail.com \
    --cc=bjorn.andersson@linaro.org \
    --cc=dmitry.baryshkov@linaro.org \
    --cc=jonathanh@nvidia.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=rjw@rjwysocki.net \
    --cc=rnayak@codeaurora.org \
    --cc=stephan@gerhold.net \
    --cc=thierry.reding@gmail.com \
    --cc=ulf.hansson@linaro.org \
    --cc=viresh.kumar@linaro.org \
    --subject='Re: [PATCH 3/3] PM: domains: Add a ->dev_get_performance_state() callback to genpd' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).